Electrolytic rectifier



June 24, 1930.

F. EICHENBERGER ELECTROLYTIC RECTIFIER Filed May 28, 1923 Inventor His flztomey known by talented dune 24, i93

FERDINA EICHENBERGER, 01 AARA'U, SWITZERLAND, ASSIGNOR, BY MESNE AS- SIGNMENTS, T0 GLOEAR CORPORATION,

RATION QF NEW YORK 0F NIAGARA. FALLS, NEW YORK, A CORPO- ELEGTEOLYTIC RECTIFIER Application filed Ittfay 28, 1923, Serial No. 642,105, and in Switzerland June 30, 1922.

' The present invention relates in general to rectifiers of the asymmetric type, that is, the type capable of passing an electric current in only one direction, and it has more particular relation to devices especially adapted for rectifiers of the electrolytic type.

Asymmetric rectifiers find considerable application in the electrical art for the purpose of converting alternating to direct current; and more particularly, electrolytic rectifiers of this class, aside from their use as converters, have well known and understood uses as condensers, lightning arresters, and the like. lhe essential features of these rectifiers are a plurality of electrodes of suitable composition immersed in or surrounded by a suitable fluid medium or electrolyte, the essential characteristic of the combination being that, during normal operation, electric current is permitted to pass in only one direction through the fluid e ectrolyte between the electrodes. Up to the present time, the socalled aluminum cell has received by far the greatest recognition as an electrolytic rectifier.

The present invention contemplates and includes a rectifier of this general type wherein new elements or parts are incorporated so as to produce a rectifier of highly desirable characteristics. More particularly, the invention includes the utilization of my discovery that metallic silicon, certain alloys of the same and products which arisewhen silicon carbide is heated sufiiciently high and under such conditions as to wholly or partly change the same into metallic silicon, when used for electrodes of rectifiers, are possessed of desirable properties or characteristics. Suitable electrodes may readily be prepared in accordance with processes heretofore made me, a suitable process involving the moldlng of a formed body, preferably in the shape of a' block or rod, from a comminuted mixture containing silicon carbide as an essential ingredient, and modifying materials, such as a'metal, calcium-carbonate, iron-oxide, and carbon, in proportions depending upon the desired mechanical characteristics, particularly self-sustaining strength, current-carrying capacity, and surface area, and the desired electrical resistance thereof. With the above described mixture rendered workably plastic through the use of a suitable amount of binder, the mixture is pressed or rammed within a mold of desired shape, preferably rod-shape; and after bakin or dryin the formed body with in the mold to a su cient extent to remove moisture and'to harden the body sufliciently to permit handling, the formed bodies are burned at a relatively high temperature, preferably in excess of 1400 C. The result of the burning is to produce a relatively hard body wherein particles of the originally comminuted mixture are altered, particularly the silicon carbide, the particles of which are so transformed as to produce a relatively homo eneous mass extending throughout the body. is the heating progresses at and upwardly oi the above mentioned temperature, more and more of the original carbon content is oxidized and metallic silicon is formed, probabl from a breaking up and oxidizing of the car 11 of the silicon carbide particles which are most thoroughly exposed to air or other oxidizing agents. A greater amount of metallic silicon may be formed in those portions of the bar, such as the terminals thereof, where it is desired that the conductivity be increased.

With an electrode of such material formed to suitable shape, for instance, a bar or plate, and in combination with another suitable electrode surrounded by a suitable medium, the rectifier is capable of efiicient operation in accordance with which the electric current is caused to flow through the device in only one direction, an operation simllar to valve action or efiect. A second electrode in a rectifier of the electrolytic type may be composed essentially of iron which is well adapted for the purpose, and a saturated solution of soda may be used as the electrolyte.

It is an object of the present inventlon to provide an improvement in the art of asymmetric rectifiers and the like involving the use of electrodes formed from silicon or products including the same.

This and other objects and advantages are attained by the present invention, various novel features of which will be apparent from the descri tion and drawings herein, disclosing an embodiment of the invention, and W111 be more particularly pointed out in the claims.

In the drawing:

Fig. 1 shows, in sectional elevation, a rectifier of the electrolytic type embodying features of the invention; and Fig. 2 1s a plan view of the device shown in Fig. 1.

In the drawing, 10 indicates an electrode, anode, the casing, itself, of the rectifier being of iron and constituting this electrode. One or more additional electrodes, cathodes, 12 are provided, the same near the periphery thereof as indicated, these electrodes 12 passing through insulators 13 in an upper wall of the receptacle the electrodes and their insulators being arranged in fluid-tight relation in the wall. The electrodes are essentially a roduct containing silicon, preferably distri uted or disposed at the surface of that portion of the electrode projectin into the receptacle 10. The receptacle is filled with a suitable electrolyte 14, preferably a suitable soda solution as described hereinabove to such a point as to maintain that portion of the electrodes 12 prejecting into the receptacle wholly immersed therein. The upper wall of the receptacle has a central upwardly projecting cone-shaped extension, as indicated, with a central openin having a closure 15 which is provided wlth a gas-discharge tube 16. The receptacle and its contents are preferably mounted on' insulating supports or feet As indicated herein, the rectifier may be of sim le form wherein all of the cathode electro es 12 are connected together so as to constitute, in efiect, a single cathode, in which case, with the electrodes connected to an alternatin current supply circuit, only unidirectiona current, such as passes from electrode 10, through the electrolyte, to electrodes 12, will flow therethrough and through any device such as a storage battery, connected in circuit therewith. There is no appreciable reversal of this current during operation, that is, as long, at least, as the voltage does not exceed a certain value. B maintaining the iron receptacle well fille as indicated, the internal resistance of the device is maintained at a low value.

Independently of the amount of silicon contained in the body or immersed portion of the electrodes 12, it is desirable that the external terminals of these electrodes be of relatively high silicon content so as to insure connections of relativel low resistance, as described in my earlier led applications.

A group of solutions other than that described hereinabove, may be used as elecbe1ng in the form' of bars equally'spaced about the receptacle trolyte, for instance, caustic, lye or potassium hydrate. Likewise, for higher voltages, the solution of the electrolyte may be correspondingly diluted.

It will be obvious that the electrodes may be arranged with respect to each other in many ways known in the art for the purpose of improving the smoothness of the direct current produced in the circuit or improving the condenser effect and the like.

It should be understood that the invention claimed is not limited to the exact details of construction and operation shown and described, for various modifications within the scope of the invention will be apparent to persons skilled in the art to which this invention relates.

It is claimed and desired to secure by Letters Patent:

1. An electrolytic rectifier, comprising an anode, and a cathode essentially and substantially composed of silicon immersed in an electrolyte.

2. An electrolytic rectifier, comprising an anode in the form of a receptacle of inactive material, and a plurality of cathodes containing silicon immersed in an electrolyte in said receptacle.

3. An electrode for electrolytic rectifiers adapted for immersion therein and having a portion adapted for exposure to the electrolyte composed essentially of silicon and silicon carbide.

4. An electrode for a rectifying system consisting of a heat-treated element formed from a mixture containing silicon carbide, iron oxide and a free metal, and having a surface portion containing silicon as an essential and substantial constituent.

5. An electrode for a rectifying system consisting of aheat-hardened element formed from a mixture containin silicon carbide as an essential and substantial constituent and having one portion thereof of eater electrical conductivity than anoti er portion thereof.

6. An electrode for a rectifying system consisting of a heat-hardened element formed from a mixture containing silicon carbide as an essential and substantial constituent and having a terminal portion provided with metallic particles intimately united with the silicon carbide particles at one terminal of the element.

7. An active electrode for electrolytic rectifiers in the form of a heat-treated body containing silicon carbide and particles of silicon intimately united therewith.

8. An asymmetric electrical current rectifier including an active composition element in the normal current path, said element being formed from silicon carbide and having a surface portion containing silicon as an essential constituent.

9. In an asymmetric rectifier for alternat-- ing currents, an active rectifying element including an alloy of silicon and silicon carbide as an essential constituent 10. An alternating electric current rectifier, comprisin a metal rectifying electrode composed principally of silicon, together with an aqueous electrolyte and a non-rectifying electrode.

11. A rectifier for alternating electric currents of low frequency, comprising an electrode having an active rectifying surface composed principally of silicon, together with an aqueous electrolyte and a non-rectifying electrode.

12. An electrolytic rectifier for alternating electric currents of low frequency, including an active electrode containing silicon of high purity in amount to efl'ect rectification in combmation with an inactive electrode and an aqueous electrolyte.

13. An electrolytic rectifier cathode element substantially comprised of metallic silicon absorbed in a basic structure of silicon carbide in which the surface exposed to the electrolyte consists substantially of metallic silicon.

14. An electrolytic rectifier cathode element substantially comprised of silicon and silicon carbon alloy formed in a silicon carbide base whereby the composition adjacent the electrol e in the operation of the rectifier consists su tantially of silicon and silicon carbon alloy.

In witness whereof, I aflix my signature hereto.

FERDINAND EIOHEN BERGER. 

